I've been targeting taking ½ my portfolio gains. As the portfolio grows I can increase my withdrawals. This also builds a legacy for my kids.

Portfolios go up and down; so you can adjust your withdrawals

In my case, a big chunk is in Canadian Registered Retirement Income Funds. The drawback is that the entire amount is taxable income in the year you die making a big chunk taxed at the top rate. You might want to carry insurance to cover the tax hit in case of sudden demise. A diagnosis giving you a few years allows you to spread the withdrawals over your remaining time in a lower tax bracket.